The Children's Hospital and Dana-Farber Cancer Institute proposes to participate as a member of the Pediatric Oncology Group (POG) in the scientific design and execution of cooperative and multi-disciplinary clinical research studies of childhood cancer. The objectives of this program are: 1. To imptove patient care and overall survival for children with cancer through participation in cooperative clinical research studies in the Pediatric Oncology Group. 2. Examine the biology of neoplasia in childhood solid tumors and leukemias through continued efforts in our own laboratories and in conjunction with the Tumor Biology Committee of POG. 3. Evaluate new approaches to cancer therapy in such areas as new agent development and supportive care. During the past several decades The Children's Hospital and Dana-Farber Cancer Institute have demonstrated a fine record of scientific contributions to the field of Pediatric Hematology and Oncology. The need for collaborative, multi-disciplinary protocols has been increasingly apparent to us over the past few years. We participated in the POG osteosarcoma study as a co-principal investigator and have established a childhood acute leukemia consortium. We wish to expand our collaborative efforts within the confines of the Pediatric Oncology Group.